Dimensions (In.)
Watt
Model Voltage Phase kW
Density
ABC
NWH-3625 1 or 3
Δ 6 47.7 32-15/16 22-1/2 16-1/2
NWH-3925 1 or 3
Δ 9 47.5 32-15/16 22-1/2 16-1/2
NWH-31225 1 or 3
Δ 12 46.2 42-15/16 32-1/2 26-1/2
NWH-31525 1 or 3
Δ 15 45.9 55-7/16 45 39
NWH-31825 1 or 3
Δ 18 45.6 55-7/16 45 39
Chromalox
®
DIVISION
4
SECTION
NWH
SALES
REFERENCE
DATE
SERVICE REFERENCE
Installation Operation
and
RENEWAL PARTS IDENTIFICATION
PE405-6
JULY, 1990
(Supersedes PE405-5)
161-048380-001
GENERAL
INSTALLATION
© 2010 Chromalox, Inc.
Type NWH-3
Circulation Heater
for Water Heating
The NWH-3 series is a general-purpose water or water-based
solution circulation heater intended for use indoors. It is designed
for 150 psig at 550˚F per ANSI standards.
The 3 copper-sheathed tubular elements are centered in a 3”
diameter galvanized steel heating chamber and welded to a
removable galvanized steel flange. The assembly is surrounded
by 1-1/2” insulation and sheet metal jacket.
Depending upon the order specifications, the NWH-3 may or
may not be factory equipped with an AR or other Chromalox
thermostat. Such thermostats function to control outlet tempera-
tures and to limit internal temperatures under abnormal flow con-
ditions. These controls do not fail safe.
CAUTION: Users should install adequate back-up controls
and safety devices with their electric heating equipment.
Where the consequences of failure may be severe, back-
up controls are essential. Although the safety of the
installation is the responsibility of the user, Chromalox
will be glad to make equipment recommendations.
CAUTION
: Hazard of Electric Shock. Disconnect all
power before installing heater.
1. Vertical Mounting (Preferred) —
When the heater is vertically mounted, the terminal housing
will be at the top of the heater. The water inlet pipe will be located on
the side near the bottom of the heater and the outlet pipe at the top.
The axis of the chamber will be in a vertical position as in
the photo above, and as in Figure A.
Note: A drain pipe located at the bottom of the heater should
be provided and enough room left, when mounting heater, to
allow draining the heater.
2. Horizontal Mounting (Optional) —
When mounting heater horizontally, inlet and outlet pipes
must be up. In any other position, heater cannot be purged of air,
and elements may be seriously damaged. (See Figure B.)
Specifications — Table A
Incorrect
Correct
Figure A — Vertical Mounting
Figure B — Horizontal Mounting
Correct
Incorrect
A
C
B
F
12-5/16”
Thermostat
Type AR
Mounting Lugs
3/8” - 16
Threaded Holes -
1-1/2” Deep
1-1/4” Centers
1” Pipe Inlet
1” Pipe
Outlet
1-3/8” Conduit
Openings
D
240
or
480
E
OPERATION
1. Do not heat solutions that are corrosive to the heating element
sheath or the heating chamber.
WARNING: Type NWH Circulation Heaters are
equipped with copper heating elements and galva-
nized-steel heating chambers. It is the responsibil-
ity of the user to know the chemical composition
of the corrosive solution and the character of the
materials entering the solution as well as the cor-
rosive effect of the solution upon the heating ele-
ments and chamber. Chromalox cannot warrant
any electric circulation heater against failure by
sheath corrosion if such failure is the result of
operating conditions beyond our control.
2. Terminal ends of heater must be protected from drippings,
condensation, spray or direct spill-over of material. Their
presence at the terminals may damage heater electrical insula-
tion. Liquid-tight terminal enclosures are available to protect
heater. Contact your Local Chromalox Sales office.
3. If foreign material is carried by the liquid flow, install suitable
filters in the inlet pipe line to the heater.
4. Do not allow heater to operate when liquid flow is interrupted.
MAINTENANCE
1. WARNING:
Hazard of Electric Shock. Disconnect all
power before servicing heater.
2. Remove heating element assembly periodically to check
heater sheath for scaling, corrosion or excessive oxidation.
Correct operating conditions to minimize sheath deterioration.
3. Periodically check temperature control and limit control oper-
ation to insure accurate and safe process operation.
4. Check all electrical connections periodically and retighten
connections which may have loosened in service. Replace wire
and wire terminals which show signs of oxidation which would
interfere with establishment of reliable electrical connections.
WIRING
WARNING: Hazard of Electric Shock. Any installation
involving electric heaters must be effectively ground-
ed in accordance with the National Electrical Code to
eliminate shock hazard.
1. Be sure line voltage matches heater voltage (on nameplate).
2. Electric wiring to heater must be installed in accordance with
local and National Electrical Codes.
3. Power controllers must be used when heaters are rated 3 phase and
when the heater amperage exceeds the rating of the thermostat.
4. Refer to Wiring Diagram, Table B, for the proper wiring diagram
for connecting
heater.
Wiring Diagrams - Table B
INSTALLATION
3. Whether vertically or horizontally, the heater should be rigidly
mounted so that vibration is at a minimum since excessive
vibration will result in erratic thermostat operation. The
NWH-3 is provided with mounting lugs to support the heating
chamber. (See photo.)
4. By using a slotted mounting assembly on either of the lugs,
the heater chamber will be permitted to expand with increas-
ing temperature.
5. DANGER: Hazard of Fire. Provide minimum of 6” spac-
ing from chamber and related piping to nearest combustible
material. Avoid operation of heater near combustible fluids or
in combustible vapor or gas laden atmosphere.
6. Provide adequate space at terminal end to permit withdrawal
of the heater from chamber should servicing be required.
Model
240V, 240V, 480V, 480V,
1 Ø Fig. 3 Ø Δ Fig. 1 Ø Δ Fig. 3 Ø Δ Fig.
NWH-3625 2 1 2 1
NWH-3925 2 1 2 1
NWH-31225 2 1 2 1
NWH-31525 2 1 2 1
NWH-31825 2 1 2 1
Ground
Contactor
Thermostat
L1
L2
L3
120V
or
240V
Note: Dotted lines indicate “customer furnished.” However, Thermostat could have been furnished by Chromalox if so specified on the order.
Figure 1
240V, 480V 3ØΔ
Figure 2
240V, 480V, 1Ø
Use contactor when the heater amperage
exceeds the rating of the thermostat.
Ground
Contactor
Thermostat
Line
120V
or
240V
AR2525 MF7
Model Volts Phase kW Heating Elements
Thermostat Assembly Thermostat Assembly
NWH-3625 240 1 6 155-024796-001 300-057560-007 300-048481-006
NWH-3625 240 3Δ 6 155-024796-002 300-057560-007 300-048481-006
NWH-3625 480 1 6 155-024796-003 300-057560-007 300-048481-006
NWH-3625 480 3Δ 6 155-024796-004 300-057560-007 300-048481-006
NWH-3925 240 1 9 155-024796-006 300-057560-007 300-048481-006
NWH-3925 240 3Δ 9 155-024796-007 300-057560-007 300-048481-006
NWH-3925 480 1 9 155-024796-008 300-057560-007 300-048481-006
NWH-3925 480 3Δ 9 155-024796-009 300-057560-007 300-048481-006
NWH-31225 240 1 12 155-024796-011 300-057560-007 300-048481-006
NWH-31225 240 3Δ 12 155-024796-012 300-057560-007 300-048481-006
NWH-31225 480 1 12 155-024796-013 300-057560-007 300-048481-006
NWH-31225 480 3Δ 12 155-024796-014 300-057560-007
NWH-31525 240 1 15 155-024796-016 300-057560-007 300-048481-006
NWH-31525 240 3Δ 15 155-024796-017 300-057560-007 300-048481-006
NWH-31525 480 1 15 155-024796-018 300-057560-007 300-048481-006
NWH-31525 480 3Δ 15 155-024796-019 300-057560-007 300-048481-006
NWH-31825 240 1 18 155-024796-021 300-057560-007 300-048481-006
NWH-31825 240 3Δ 18 155-024796-022 300-057560-007 300-048481-006
NWH-31825 480 1 18 155-024796-023 300-057560-007 300-048481-006
NWH-31825 480 3Δ 18 155-024796-024 300-057560-007 300-048481-006
RENEWAL PARTS IDENTIFICATION
PARTS COMMON TO ALL HEATERS
AR Mounting Bracket . . . . . . . . . . . . . . . . .027-011378-001 (2)
Flexitallic Gasket . . . . . . . . . . . . . . . . . . . . . .132-019779-001
Standard Gasket . . . . . . . . . . . . . . . . . . . . . . .132-017222-001
Note: When ordering parts for Model Numbers suffixed by “XX” or any other letter or letters not specifically identified on this instruction sheet, order Renewal
Parts on special order basis, giving name of part, part number, model number and description.
Note: Number in ( ) indicates quantity of same part number used.
2150 N. RULON WHITE BLVD., OGDEN, UT 84404
Phone: 1-800-368-2493 www.chromalox.com
PL - U0 - T3
Litho in U.S.A.
Limited Warranty:
Please refer to the Chromalox limited warranty applicable to this product at
http://www.chromalox.com/customer-service/policies/termsofsale.aspx.
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